On the first iteration you set lastInt to anotherInt. lastInt->nextNode is presumably a null or invalid pointer. Then, rather than storing fileInt (which by the way the loop doesn't even touch, nor does it touch intInputFile) in lastInt->intValue, you move lastInt to the next node, which isn't guaranteed to exist, and assign to that the integer.

This is a problem because you never initialized anotherInt->nextNode. Depending on what you're doing in intNode's constructor, you're either dereferencing a null pointer (bad), or dereferencing an uninitialized pointer (worse). Each have potential to crash.